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H.|P. MAXIM SLLENCER Original FleEMach 25. 1922;

May 21, 1 929.

2, )QLVVENTOR Zm ATTORNEY a n Reissued May 21, 41921-9.

UNITED STATES j Re. 17,299 e PATENT OFFICE.

HIRAM PERCYMAXIM, 0F HARTFORD, CONNECTICUT, ASSIGNOR TO THE SILENCER COMPANY, O F HARTFORD, CONNECTICUT, A CORPORATION OF CON- NECTICUT.

Original application filed March 23, 1922, Serial-No. 546,126. Divided 1926, Serial No. 138,996. OriginaI No. 1,636,238, 4dated July 19, 1927-. Application for -reissue 111er!4 March 1'5, 192s. serial No. 261,967.-

The present invention relates to'silencers or muiilers such as are used in connection with gas or oil engines to reduce the noiseof the exhaust or in connection ywith various kinds 5 of steam and pneumatic machinery for dead.-

enng the discharge or intake noises thereof.

The invent-ion is particularly directed to improvements inthe type of silencers de* scribed generally in my Patent 1,611,47 5 l0 granted December 21, 1926, of Which this present application is a division.:

. One object fof the invention is to provide a muilier or silencer of the general character above mentioned which will eifectively perform its functions Without creating back pressure. l

To this end, the invention contemplates broadly the provision, in an exhaustor .intake silencer, of a silencing conduit constructed and arranged to obstruct the escape of the sound Waves without throttling the fioW of the sound propagating medium.A

, In carrying out this feature of-this invention, the silencing conduit is made to comprise at leasty one section, the Walls of which are shaped in accordance with the principles of Venturi tube construction to provide -a 4gradually contracting portion and a gradu- Y ally expanding portiomthe former being arranged to discharge into the latter. As the exhaust gases passthrough a conduit constructed in this manner, the sound waves which strike the tapering walls of the contracting portions are reflected 'backwardlyg and are trapped and as a result only such sound Waves escape as pass directly through the small end of the-contracted portion without striking 'against the 'converging Walls thereof. By `reason of the Venturi action of the expanding or diverging portion of the conduit, the .velocity of the gases is increased in the restricted portion to'such an extent that the volume of flow per unit of time of said ses or propagating medium is not materialzl; reduced and consequently the ,dis charge capacity of the conduit is not reduced and no undesirable back pressure is created.

Another object of the invention is to provide certain new -and useful improvements in silencers tending to simplify their construction, increase their eiicienc'y and reduce the cost of their manufacture.

`body portion sILENcna.

' With these latter objectsin View; as will appear from the following description, the

andy application filed October 1,

and claimed, the advantages of which Will be apparent to those skilled in the art.

In the accompanying drawings:

Fig. 1 is a cross-sectional view of asilencer embodying the present invention; and

Fig. 2 is a section on line 2-2 of Fig. 1. Referring to the drawings, the silencer or muiiler therein illustrated comprises a Icylindrical easing consisting of a body portion 35` and acover plate 36 which are rigidly secured together by 4means of bolts 37, the latter extendin ears 38 on t e body and cover plate. The

vided with a'peripheral inlet spud 39 and with an axial outlet orifice 40. The interior of the'rnuier Icasing is provided with two intertwining generally scroll-shaped ribs 41 land 42 which extend from'the cover plate 36 of the cylindrical muiiier casing tothe end wall of the body portion 35 and are so arranged ns to afford two separate. spiral or involute passages 44 leading inwardly to the central-portion of the casing and through which the incoming exhaust gases must pass in orderto reach theoutlet orifice 40, To facilitate the casting'of the spiral ribs 41 and 42, the rib 41 is made integral with the body of the casing 35 while the rib 42 is made integral with the cover plate 36, this expedient providing for 'suiiicient space between the ribs of each'casting to insure that the ribs will .draw properly from the sand of the mold. To effect the trapping of the sound waves without retarding the flow of the sound prop aga-tingV medium, each spiral passage 44'is provided with a series of Venturi sections 45 ea ch of which is formed by means of a convexly curved lateral projection 46 upon one of the opposed spiral ribs which form the opposite side Walls of the passageway.4 The Venturi sections 45 have substantially. the same effect upon the exhaust gases and sound waves as the Venturi sections described in connection with the silencer described in my through outwardly projecting of the-muffler casing is pro- Patent 1,611,475 granted December 21, 1926,

` practical Way of embodying Venturi secbolted together.

rin 'opposed tions in a silencing conduit of spiral form, a

considerable economy of space is eifected.'

The particular construction described is of extremely ysimple and rugged construction and is inexpensive to manufacture, the mutfler comprising only two castings which are It will be understood that the invention may he embodied in various other forms than that shown and that many changes in the-details of construction and arrangement 'ot parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What l claim is:

1. A silencer comprising, a ,cylindrical casing having a peripheral andan axial opening therein, a silencing conduit of spiral form within said casing extending between said openings, said conduit having a succession ot contracting and expanding sections distributed throughout its length to form a series of Venturi-like passageways therein.

2. A silencer comprising, a pair of castings -each having an integral spiral flange eX- 'tending `from a side face thereof, said castsecured together with said flanges intertwined relation coacting with the opposed side races to provide two s iral silencing conduits leading outwardly rom an axial chamber, and projections on said flanges cooperating with the adjacent flanges to provide a series ot contracting and expanding sections of Venturilike character in said conduit.

3. A silencer v. comprising, a pairof castings each having an integral spiral ange extending from a side face thereof, said castings being secured together withv said flanges in opposed intertwined relation, saidfflanges coacting with the opposed side faces to provide two spiral silencing conduits leading outwardly from an axial chamber, yand projections on said ianges lcooperating with 4the adjacent flanges to provide a series of contracting and expanding-sections 'of like character in* said conduit;y one of said castings having an outer circular flange inings being tegral therewith and Vcoacting with said other casting to provide an annular chambery surfrom a side face thcreo t, said castings being Said flanges. members, a plurality on said partitions cooperating with the adsaid circular rounding said spiral conduits,

the 1nhaving'an integral spiral iiange extending secured together with said spi 'al flanges in opposed intertwined relation. said spiral flanges coacting with the opposed side 'faces to provide a central chamber having an axial opening and two spiral silencing conduits leading outwardly from said chamber, said circular flange coacting with said diskshaped casting to provide an annular chamber surrounding said spiral conduits, and convex projections on said spiral ilangcs co-4 operating with the adjacent flanges to provide a series of contracting and expanding sections of Venturi-Eike character in said conduits. y

5. A silencer comprising a conduit of involute form having a succession of contracting and expanding sections' distributed throughout its length constructed :1nd arranged to trap the sound waves without impeding the flow of exhaust gases.

6. A silencer'comp'rising a pair of end of intertwined involutc partitions spaced apart between said end members toprovide spiral silencing conduits leading outwardly from a central receiving chamber, a plurality of convexprojections jacent partitions to provide contracting and enlargingv sections in said conduits to trap the sound waves without impeding the flow ol exhaust gases.

7. A silencerV comprising a plurality of.

8. A silencer comprising a plurality of spirally arranged overlapping conduits each having an alternating succession ot Venturilike restricted portions and enlarged expansion chambers. i,

In testimony' whereof I have aflixed my signature.

y `I-IIRAM PERCYyMAXIM. 

